Salt can only do so much. It works by making your blood thicker and increasing the amount of water your body can hold onto (salt is an electrolyte) and hydration generally helps. Personally it doesn’t help that much as far as prevention goes. But if I’m feeling particularly shitty (or after I pass out) I’ve found that chugging a liquid IV and eating a shit ton of salty snacks helps make me feel better. My recommendation is compression socks. Compression garments in general.
I take a prescription med called corlanor/ivabradine which significantly reduces how much I pass out. Other than that just lying down frequently helps a lot. If you want to try the salt pills you can get them prescription or just on Amazon or something. In my case they are a bit cheaper prescription but I’m sure it depends. I also recommend eating with them cuz I get super nauseated if I don’t. Good luck 🙏